"We have again delivered a quarter of solid operational and financial performance," said John W. Rowe, chairman and chief executive officer. "Exelon Generation's nuclear fleet produced a capacity factor of 89.6 percent even with 103 planned refueling outage days, and our delivery companies ComEd and PECO performed well despite the challenges of severe weather conditions. Reflecting our first half results and confidence in our outlook for the remainder of the year, we are raising our operating earnings guidance range to $4.05 to $4.25 per share from $3.90 to $4.20 per share."

Second Quarter Operating Results

As shown in the table above, Exelon's adjusted (non-GAAP) operating earnings increased to $1.05 per share in the second quarter of 2011 from $0.99 per share in the second quarter of 2010, primarily due to:• The effect at Exelon Generation Company, LLC (Generation) of higher realized energy prices in the Mid-Atlantic region due to the expiration of the power purchase agreement (PPA) with PECO Energy Company (PECO) and favorable market and portfolio conditions including wind and hydro volume; • Benefits from a special transfer tax deduction related to nuclear decommissioning trust (NDT) funds; • One-time net benefits reflecting the 2011 electric distribution rate case order for Commonwealth Edison Company (ComEd); and• The effect of new electric and gas distribution rates at PECO effective January 1, 2011.

Adjusted (non-GAAP) operating earnings for the second quarter of 2010 did not include the following items (after tax) that were included in reported GAAP earnings: (in millions) (per diluted share)Mark-to-market losses primarily from Generation's economic hedging activities $(75) $(0.11)Non-cash remeasurement of income tax uncertainties related to ComEd's 1999 sale of fossil generating assets and related to CTCs received by PECO $(65) $(0.10)Unrealized losses related to NDT fund investments to the extent not offset by contractual accounting $(53) $(0.08)Financial impacts associated with the planned retirement of certain Generation fossil generating units $(12) $(0.02)Costs associated with the 2007 Illinois electric rate settlement agreement $(4) $(0.01)Costs associated with ComEd's 2007 settlement agreement with the City of Chicago $(2) -

2011 Earnings Outlook

Exelon raised its guidance range for 2011 adjusted (non-GAAP) operating earnings to $4.05 to $4.25 per share from $3.90 to $4.20 per share. Operating earnings guidance is based on the assumption of normal weather for the balance of the year.

The outlook for 2011 adjusted (non-GAAP) operating earnings for Exelon and its subsidiaries excludes the following items:• Mark-to-market adjustments from economic hedging activities• Unrealized gains and losses from NDT fund investments to the extent not offset by contractual accounting as described in the notes to the consolidated financial statements• Significant impairments of assets, including goodwill• Changes in decommissioning obligation estimates• Non-cash charge to remeasure deferred taxes at higher Illinois corporate tax rates• Financial impacts associated with the planned retirement of fossil generating units• One-time benefits reflecting ComEd's 2011 distribution rate case order for the recovery of previously incurred costs related to the 2009 restructuring plan and for the passage of Federal health care legislation in 2010• Certain costs associated with the Exelon's proposed merger with Constellation• Other unusual items• Significant changes to GAAP

Second Quarter and Recent Highlights

• Proposed Merger with Constellation: On April 28, 2011, Exelon entered into a merger agreement with Constellation which contemplates a stock-for-stock transaction. Constellation is a leading competitive supplier of power, natural gas and energy products and services for homes and businesses across the continental United States. It owns a diversified fleet of generating units, totaling approximately 12,000 megawatts (MW) of generating capacity, and delivers electricity and natural gas through the Baltimore Gas and Electric Company (BGE), its regulated utility in central Maryland.

Constellation's shareholders will receive 0.930 shares of Exelon common stock in exchange for each share of Constellation common stock. Following completion of the merger, Exelon shareholders will own approximately 78 percent of the combined company and Constellation shareholders approximately 22 percent on a fully diluted basis. The closing of the merger is dependent upon the receipt of all required approvals, including approval of the shareholders of both companies. Exelon and Constellation expect the closing of the merger to occur in early 2012.

• Nuclear Regulatory Commission (NRC) Task Force Report: On July 12, 2011, the NRC Near-Term Task Force issued its report, which reviewed nuclear processes and regulations in light of the accident at the Fukushima Daiichi plant in Japan. The Task Force concluded that U.S. nuclear plants are operating safely and did not identify changes to the existing nuclear licensing process nor recommend fundamental changes to spent nuclear fuel storage. The Task Force report made recommendations in three key areas: the NRC's regulatory framework, specific plant design requirements, and emergency preparedness and actions. Exelon expects the report to be the first step in a longer-term review that the NRC will conduct, along with seeking broad stakeholder input. Exelon continues to apply lessons learned and work with regulators and industry organizations on appropriate assessments and actions.

• Nuclear Operations: Generation's nuclear fleet, including its owned output from the Salem Generating Station, produced 33,167 gigawatt-hours (GWh) in the second quarter of 2011, compared with 35,035 GWh in the second quarter of 2010. The Exelon-operated nuclear plants achieved an 89.6 percent capacity factor for the second quarter of 2011 compared with 94.8 percent for the second quarter of 2010. The Exelon-operated nuclear plants completed four scheduled refueling outages in the second quarter of 2011, compared with completing three scheduled refueling outages in the second quarter of 2010. The number of refueling outage days totaled 103 in the second quarter of 2011 versus 44 days in the second quarter of 2010. The number of non-refueling outage days at the Exelon-operated plants totaled 24 days in the second quarter of 2011 compared with 15 days in the second quarter of 2010.

• Nuclear License Renewals: On June 30, 2011, the NRC approved extension of the operating licenses for the Salem Generating Units 1 and 2 by 20 years to 2036 and 2040, respectively. Exelon has a 42.59 percent ownership interest in these units, which are operated by PSEG Nuclear, LLC.

On June 22, 2011, Exelon submitted an application to the NRC to extend the operating licenses of Limerick Generating Units 1 and 2 by an additional 20 years. The current licenses of the units expire in 2024 and 2029, respectively. The NRC is expected to spend 22 to 30 months reviewing the application before making a decision.

• Fossil and Hydro Operations: The equivalent demand forced outage rate for Generation's fossil fleet was 4.9 percent in the second quarter of 2011, compared with 3.8 percent in the second quarter of 2010. The increase was largely due to an outage in 2011 at a unit at the Handley Generating Station. The equivalent availability factor for the hydroelectric facilities was 93.4 percent in the second quarter of 2011, compared with 98.1 percent in the second quarter of 2010, largely due to planned outages in April at two units at the Muddy Run facility.

• Acquisition of Wolf Hollow: On May 12, 2011, Exelon announced an agreement to acquire Wolf Hollow, a combined-cycle natural gas-fired power plant in north Texas, from Sequent Wolf Hollow, LLC, for $305 million, as adjusted for working capital. The transaction adds 720 MW of clean energy to Exelon's fleet in the competitive Electric Reliability Council of Texas (ERCOT) power market, where the company already owns and operates three other natural gas-fired power plants. Exelon currently has a PPA with Wolf Hollow, through 2023, to purchase 350 MW of its output at above current observable market power prices. In addition to eliminating the existing PPA, Exelon expects the proposed transaction to provide incremental cash flows beginning in 2012. The Wolf Hollow transaction is subject to antitrust clearance and approval by the Public Utility Commission of Texas. Exelon plans to finance the transaction with existing cash flow and liquidity resources and expects to close in the third quarter of 2011.

• Hedging Update: Exelon's hedging program involves the hedging of commodity risk for Exelon's expected generation, typically on a ratable basis over a three-year period. Expected generation represents the amount of energy estimated to be generated or purchased through owned or contracted-for capacity. The proportion of expected generation hedged as of June 30, 2011 is 95 to 98 percent for 2011, 82 to 85 percent for 2012 and 49 to 52 percent for 2013. The primary objectives of Exelon's hedging program are to manage market risks and protect the value of its generation and its investment grade balance sheet while preserving its ability to participate in improving long-term market fundamentals.

• Reliability Interregional Transmission Extension (RITE) Line: On July 18, 2011, Exelon and Electric Transmission America (ETA), a joint venture of American Electric Power (AEP) and MidAmerican Energy Holdings, filed for a formula rate and incentives at FERC for a proposed 420-mile, 765-kilovolt (kV) transmission line called the RITE Line. The RITE Line will interconnect with the existing AEP 765-kV system at the Indiana/Ohio border and extend west through Indiana into Illinois, connecting with the ComEd system and extending to a new 765-kV substation near Byron, Illinois. The RITE Line will allow reliable interconnection to additional sources of energy, including renewables. The project will be built in stages over three to four years, likely between 2015 and 2018, and in addition to FERC is subject to PJM Interconnection, LLC and state approvals. The FERC filing is a significant step in the process of obtaining these approvals for the line.

• ComEd Electric Distribution Rate Case: On June 30, 2010, ComEd filed a rate increase request with the Illinois Commerce Commission (ICC) to allow the utility to continue modernizing its electric delivery system and recover the cost of substantial investments made since the last rate filing in 2007. In subsequent testimony, ComEd revised its requested revenue increase to $343 million, reflecting certain adjustments to its original request of $396 million. On May 24, 2011, the ICC issued its final order in the rate case. ComEd received a revenue increase of $143 million, which became effective on June 1, 2011. The approved rate of return on common equity is 10.50 percent.

• Illinois Proposed Energy Infrastructure and Modernization Act: On May 31, 2011, the Illinois General Assembly passed legislation (Senate Bill 1652) that will modernize Illinois' electric grid if enacted into law. The legislation includes a policy-based approach that would provide a more predictable ratemaking system and would enable utilities to modernize the electric grid and set the stage for fostering economic development while creating and retaining jobs. The legislation also includes a process for determining formula rates that would provide for the recovery of actual costs of service that are prudent and reasonable. Once the legislation is presented to the Governor, he will have 60 days to act on it.

Second quarter 2011 net income was $443 million compared with $382 million in the second quarter of 2010. Second quarter 2011 net income included (all after tax) mark-to-market losses of $75 million from economic hedging activities, net costs of $10 million associated with the planned retirement of certain fossil generating units, unrealized gains of $6 million related to NDT fund investments and certain costs of $1 million associated with the proposed merger with Constellation. Second quarter 2010 net income included (all after tax) mark-to-market losses of $75 million from economic hedging activities, a gain of $70 million related to the non-cash remeasurement of income tax uncertainties, unrealized losses of $53 million related to NDT fund investments, costs of $12 million associated with the retirement of certain fossil generating units and a charge of $4 million for costs associated with the 2007 Illinois electric rate settlement. Excluding the effects of these items, Generation's net income in the second quarter of 2011 increased $67 million compared with the same quarter in 2010 primarily due to:• The impact on energy gross margin of higher realized energy prices in the Mid-Atlantic region due to the expiration of the PPA with PECO, coupled with favorable market and portfolio conditions including wind and hydro volume; and• Benefits from the special transfer tax deduction related to NDT funds.

Generation's average realized margin on all electric sales, including sales to affiliates and excluding trading activity, was $41.59 per MWh in the second quarter of 2011 compared with $36.87 per MWh in the second quarter of 2010.

ComEd consists of the electricity transmission and distribution operations in northern Illinois.

ComEd recorded net income of $114 million in the second quarter of 2011, compared with net income of $9 million in the second quarter of 2010. Second quarter net income in 2011 included an after-tax non-cash credit of $17 million for the recovery of previously incurred costs pursuant to the 2011 distribution rate case order. Second quarter net income in 2010 included an after-tax charge of $106 million related to the non-cash remeasurement of income tax uncertainties and after-tax costs of $2 million for the City of Chicago settlement agreement. Excluding the effects of these items, ComEd's net income in the second quarter of 2011 was down $20 million from the same quarter in 2010 primarily reflecting:• The recording in 2010 of projected refunds related to Illinois electric distribution taxes;• Higher operating and maintenance expenses; and• Increased depreciation and interest expenses.

The decrease in net income was partially offset by:• One-time net benefits pursuant to the 2011 electric distribution rate case order; and• The impact of new electric distribution rates effective June 1, 2011.

In the second quarter of 2011, cooling degree-days in the ComEd service territory were down 24.0 percent relative to the same period in 2010 and were 5.8 percent above normal. Total retail electric deliveries decreased 2.3 percent quarter over quarter.

Weather-normalized retail electric deliveries decreased 0.8 percent in the second quarter of 2011 relative to 2010, reflecting a decrease in deliveries to all major customer classes. For ComEd, weather had an unfavorable after-tax effect of $4 million on second quarter 2011 earnings relative to 2010 and a favorable after-tax effect of $1 million relative to normal weather that is incorporated in Exelon's earnings guidance.

PECO consists of the electricity transmission and distribution operations and the retail natural gas distribution business in southeastern Pennsylvania.

PECO's net income in the second quarter of 2011 was $83 million, up from $75 million in the second quarter of 2010. Second quarter 2010 net income included an after-tax interest expense charge of $22 million related to the non-cash remeasurement of income tax uncertainties. Excluding the effect of this item, PECO's net income in the second quarter of 2011 was down $14 million from the same quarter in 2010, primarily reflecting:• The effect of CTC recoveries in 2010, net of amortization expense, associated with PECO's transition period, which ended on December 31, 2010.

The decrease in net income was partially offset by:• The impact of new electric and gas distribution rates effective January 1, 2011;• Decreased storm costs; and• Lower interest expense.

In the second quarter of 2011, cooling degree-days in the PECO service territory were down 15.7 percent from 2010 and were 48.8 percent above normal. Total retail electric deliveries were down 2.5 percent from last year. On the retail gas side, deliveries in the second quarter of 2011 were up 9.8 percent from the second quarter of 2010.

Weather-normalized retail electric deliveries were about flat in the second quarter of 2011 relative to 2010, as a decline in large commercial and industrial deliveries was mostly offset by increases in deliveries to residential and small commercial and industrial customers. Weather-normalized retail gas deliveries were down 1.3 percent in the second quarter of 2011. For PECO, weather had an unfavorable after-tax effect of $4 million on second quarter 2011 earnings relative to 2010 and a favorable after-tax effect of $9 million relative to normal weather that is incorporated in Exelon's earnings guidance.

Adjusted (non-GAAP) Operating Earnings

Adjusted (non-GAAP) operating earnings, which generally exclude significant one-time charges or credits that are not normally associated with ongoing operations, mark-to-market adjustments from economic hedging activities and unrealized gains and losses from NDT fund investments, are provided as a supplement to results reported in accordance with GAAP. Management uses such adjusted (non-GAAP) operating earnings measures internally to evaluate the company's performance and manage its operations. Reconciliation of GAAP to adjusted (non-GAAP) operating earnings for historical periods is attached. Additional earnings release attachments, which include the reconciliation on pages 7 and 8, are posted on Exelon's Web site (download attachment) and have been furnished to the Securities and Exchange Commission on Form 8-K on July 27, 2011.

Conference call information: Exelon has scheduled a conference call for 11:00 AM ET (10:00 AM CT) on July 27, 2011. The call-in number in the U.S. and Canada is 800-690-3108, and the international call-in number is 973-935-8753. If requested, the conference ID number is 80732345. Media representatives are invited to participate on a listen-only basis. The call will be web-cast and archived on Exelon's Web site in the Investors section.

Telephone replays will be available until August 10. The U.S. and Canada call-in number for replays is 800-642-1687, and the international call-in number is 706-645-9291. The conference ID number is 80732345.

Cautionary Statements Regarding Forward-Looking Information

Except for the historical information contained herein, certain of the matters discussed in this communication constitute "forward-looking statements" within the meaning of the Securities Act of 1933 and the Securities Exchange Act of 1934, both as amended by the Private Securities Litigation Reform Act of 1995. Words such as "may," "will," "anticipate," "estimate," "expect," "project," "intend," "plan," "believe," "target," "forecast," and words and terms of similar substance used in connection with any discussion of future plans, actions, or events identify forward-looking statements. These forward-looking statements include, but are not limited to, statements regarding benefits of the proposed merger of Exelon Corporation (Exelon) and Constellation Energy Group, Inc. (Constellation), integration plans and expected synergies, the expected timing of completion of the transaction, anticipated future financial and operating performance and results, including estimates for growth. These statements are based on the current expectations of management of Exelon and Constellation, as applicable. There are a number of risks and uncertainties that could cause actual results to differ materially from the forward-looking statements included in this communication regarding the proposed merger. For example, (1) the companies may be unable to obtain shareholder approvals required for the merger; (2) the companies may be unable to obtain regulatory approvals required for the merger, or required regulatory approvals may delay the merger or result in the imposition of conditions that could have a material adverse effect on the combined company or cause the companies to abandon the merger; (3) conditions to the closing of the merger may not be satisfied; (4) an unsolicited offer of another company to acquire assets or capital stock of Exelon or Constellation could interfere with the merger; (5) problems may arise in successfully integrating the businesses of the companies, which may result in the combined company not operating as effectively and efficiently as expected; (6) the combined company may be unable to achieve cost-cutting synergies or it may take longer than expected to achieve those synergies; (7) the merger may involve unexpected costs, unexpected liabilities or unexpected delays, or the effects of purchase accounting may be different from the companies' expectations; (8) the credit ratings of the combined company or its subsidiaries may be different from what the companies expect; (9) the businesses of the companies may suffer as a result of uncertainty surrounding the merger; (10) the companies may not realize the values expected to be obtained for properties expected or required to be divested; (11) the industry may be subject to future regulatory or legislative actions that could adversely affect the companies; and (12) the companies may be adversely affected by other economic, business, and/or competitive factors. Other unknown or unpredictable factors could also have material adverse effects on future results, performance or achievements of Exelon or the combined company. Discussions of some of these other important factors and assumptions are contained in Exelon's and Constellation's respective filings with the Securities and Exchange Commission (SEC), and available at the SEC's website at www.sec.gov, including: (1) Exelon's 2010 Annual Report on Form 10-K in (a) ITEM 1A. Risk Factors, (b) ITEM 7. Management's Discussion and Analysis of Financial Condition and Results of Operations and (c) ITEM 8. Financial Statements and Supplementary Data: Note 18; (2) Exelon's Second Quarter 2011 Quarterly Report on Form 10-Q (to be filed on July 27, 2011) in (a) Part II, Other Information, ITEM 1A. Risk Factors, (b) Part 1, Financial Information, ITEM 2. Management's Discussion and Analysis of Financial Condition and Results of Operations and (c) Part I, Financial Information, ITEM 1. Financial Statements: Note 13; (3) Constellation's 2010 Annual Report on Form 10-K in (a) ITEM 1A. Risk Factors, (b) ITEM 7. Management's Discussion and Analysis of Financial Condition and Results of Operations and (c) ITEM 8. Financial Statements and Supplementary Data: Note 12; and (4) Constellation's Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2011 in (a) Part II, Other Information, ITEM 5.Other Information, (b) Part I, Financial Information, ITEM 2. Management's Discussion and Analysis of Financial Condition and Results of Operations and (c) Part I, Financial Information, ITEM 1. Financial Statements: Notes to Consolidated Financial Statements, Commitments and Contingencies. These risks, as well as other risks associated with the proposed merger, are more fully discussed in the preliminary joint proxy statement/prospectus included in the Registration Statement on Form S-4 that Exelon filed with the SEC on June 27, 2011 in connection with the proposed merger. In light of these risks, uncertainties, assumptions and factors, the forward-looking events discussed in this communication may not occur. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this communication. Neither Exelon nor Constellation undertake any obligation to publicly release any revision to its forward-looking statements to reflect events or circumstances after the date of this communication.

Additional Information and Where to Find it

This communication does not constitute an offer to sell or the solicitation of an offer to buy any securities, or a solicitation of any vote or approval, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. On June 27, 2011, Exelon filed with the SEC a Registration Statement on Form S-4 that included a preliminary joint proxy statement/prospectus and other relevant documents to be mailed by Exelon and Constellation to their respective security holders in connection with the proposed merger of Exelon and Constellation. These materials are not yet final and may be amended. WE URGE INVESTORS AND SECURITY HOLDERS TO READ THE PRELIMINARY JOINT PROXY STATEMENT/PROSPECTUS AND THE DEFINITIVE JOINT PROXY STATEMENT/PROSPECTUS AND ANY OTHER RELEVANT DOCUMENTS WHEN THEY BECOME AVAILABLE, BECAUSE THEY CONTAIN OR WILL CONTAIN IMPORTANT INFORMATION about Exelon, Constellation and the proposed merger. Investors and security holders will be able to obtain these materials (when they are available) and other documents filed with the SEC free of charge at the SEC's website, www.sec.gov. In addition, a copy of the preliminary joint proxy statement/prospectus and definitive joint proxy statement/prospectus (when it becomes available) may be obtained free of charge from Exelon Corporation, Investor Relations, 10 South Dearborn Street, P.O. Box 805398, Chicago, Illinois 60680-5398, or from Constellation Energy Group, Inc., Investor Relations, 100 Constellation Way, Suite 600C, Baltimore, MD 21202. Investors and security holders may also read and copy any reports, statements and other information filed by Exelon, or Constellation, with the SEC, at the SEC public reference room at 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 or visit the SEC's website for further information on its public reference room.

Participants in the Merger Solicitation

Exelon, Constellation, and their respective directors, executive officers and certain other members of management and employees may be deemed to be participants in the solicitation of proxies in respect of the proposed transaction. Information regarding Exelon's directors and executive officers is available in its proxy statement filed with the SEC by Exelon on March 24, 2011 in connection with its 2011 annual meeting of shareholders, and information regarding Constellation's directors and executive officers is available in its proxy statement filed with the SEC by Constellation on April 15, 2011 in connection with its 2011 annual meeting of shareholders. Other information regarding the participants in the proxy solicitation and a description of their direct and indirect interests, by security holdings or otherwise, is contained in the preliminary joint proxy statement/prospectus and will be contained in the definitive joint proxy statement/prospectus.